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Silica Resources for Designers
Designers hold a unique position in the construction industry, as it is with them that many health risks can be first identified and managed. Using the simplified risk management framework E.R.I.C. (eliminate, reduce, inform, and control), designers hold the best opportunity to eliminate the health risk entirely.
With respects to dust, and notably silica dust, this is the most vital step. The COSHH regulations makes a requirement to prevent the exposure to any chemical, and where there is an exposure to a carcinogen such as silica, or an asthmagen like wood dust then there is a greater need to prioritise eliminating that exposure.
If this is not thought about early enough, then the opportunity is lost and by the time a worker is picking up a drill, or breaker, then there is no chance to stop that exposure happening in the first place.
It is the role of a designer to therefore take that opportunity and design an approach that eliminates it completely. And if you can’t, then flag it up to someone who can.
Figure 1: Precast fixings cast into concrete segments (Orange), and use of fixing techniques to remove the further working of concrete (Blue).
Know Your Risks
Being aware of the risks of dust, wood and silica is a starting point. Whilst you could think these things as normal construction risks which will be managed by a “competent contractor”, inevitably this means a reliance on PPE.
If you know a chunk of work will require an unusual amount of dust exposure, make a point to raise it in the design and list it on the risk register, so that alternative approaches can be considered as soon as possible, even if you can’t think of a means to avoid it.
You may not consider concrete dust as an usual or significant risk, but the fact 500 to 800 people die every year from silica exposure to it suggests that this might not be as appreciated as we think.
Know the risks of what you specify. Silica and concrete dusts are well known about, but what about the wood you specify? Increasingly architectural finishes specify western red cedar due to its favourable finish and resilience to weather. But are you aware of the risks that this dust can pose? The risks of wood dust can be species specific, with western red cedar being a potent allergen just one example. Wood dust can have a variety of risks, be that allergic reactions, cancer, or simple irritation. If you know the species of wood then it doesn’t take much research to inform the rest of the supply chain in your designs.
Know Your Options
Working with concrete is normal practice these days for the construction industry, so we should be well aware of the options available for minimising these exposures where we can. As a designer, you might not be aware of what approach might work best for a particular project or contractor, but we can flag up options on the design so that the default of grabbing a mask is not the go to options.
• If you need to tie into to rebar then couplers should be a standard approach. Know that these will shift during pours, so specify foam inserts to minimise the amount of chasing required to located couplers.
• Cast in Halfen channels were possible.
• If rebar needs to be broken out, encased it in foam pipe insulation and wooden shuttering, to enable easy exposure of rebar by machine and removing the amount to hand trimming required.
• Low strength/pea gravel tops to pile caps or specifying weaker sacrificial concrete to fill voids possible.
• Retarders and jet washing to prepare concrete joints for sequential pours rather than scabbling or other hand tools.
If you can’t eliminate the exposure altogether then be sure to direct contractors to using engineering controls where possible, and ensure that the design can cater for these if necessary, be that a clear provision of fresh air through a building, or ability to wet cut in a given environment.
Inform People of The Risks
The earlier a risk is raised, the earlier people can plan for it. Be that finding alternative means of doing the job, and alternative technique or piece of plant, and alternative material.
You will be aware of your obligations of the Construction (Design and Management) Regulations 2015 (CDM 2015), and at its core is the requirement to inform all parties of the risks associated with a design.
The focus is often on the operation and maintenance of a building or structure, but the construction phase is just as important to concentrate on. It is this phase where the burden of health risks come into play and where they have their impact.
Where there is a risk that you cannot design out, flag it up so as to inform designers that might follow on from you, inform following on contractors, make sure that you have done your part to enable adequate planning to manage a dust risk or eliminate it completely.
Figure 2: Foam and boarding of enclosure of rebar which will be broken out for tying in to.
Figure 3: Breaking out of low strength concrete used for protecting lifting points.
Figure 4: Low strength concrete designed to protect lifting points.
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